A-D-glucopyranoside

Benzyl-2-acetamido-4,6-(7-benzylidene-2-deoxy-a-D-glucopyranoside [13343-63-0] M 399.4, m 256-261 , 263-264 , [alp +120 (c 1, pyridine). Wash with cold isoPrOH and crystallise from dioxane/isoPrOH. [/ Org Chem 32 2759 1967.]... 

Chemical Name Hexadeca-)U-hydroxytetracosahydroxyl/Ug-l 1,3,4,6-tetra-O-suifo-/3-D-fructo-furanosyl-a-D-glucopyranoside tetrakisihydrogen sulfato)(8-)] ] hexadecaaluminum... 

A mixture of d- and l- hexoses also results from the hydroboration of these 5-enes. Hydroboration results in anti-Markownikoff, cw-hydration of the double bond and the amount of each hexose formed varies according to the nature of the substituent groups. For example, hydroboration (23) of methyl 6-deoxy-a-D-ryZo-hex-5-enopyranose (3) affords methyl a-D-glucopyranoside and methyl / -L-idopyranoside in the ratio of 1 2.5 respectively whereas hydroboration of the fris-trimethylsilyl ether of 3 afforded them in the ratio 1 0.6 respectively. The hydroboration method can be used to achieve specific labelling of hexoses with tritium methyl-/ -L-idopyranoside[5-H3] and methyl a-D-glucopyranoside [5-H3] were thus prepared (23). Similarly, hydroboration of the D-Zt/ro-hex-5-eno derivative (14) with diborane-H3 followed by removal of the isopropyli-dene group, afforded methyl a-D-mannopyranoside [5-H3] and methyl / -L-gulopyranoside [5-H3] in the ratio of 1 2 respectively (23). 

Rennie (49), working in my laboratory, succeeded in converting d-glucose into 4-deoxy-D-Jct/Zo-hexose, albeit with considerable difficulty, by the following sequence of reactions which incorporate mercaptalation of the carbonyl group and reductive desulfurization of the dithiol 1 2 D-glucose methyl 2,3-di-0-benzyl-6-0-trityl-a-D-glucopyranoside - ... 

These observations reported in the mid-30 s on the relative reactivities of the C-4 and C-6 tosylates toward a nucleophile such as sodium iodide, lay dormant until 1963, when it was found (60) that treatment of methyl 2,3-di-0-benzoyl-4,6-di-0-methylsulfonyl-a-D-glucopyranoside (14) with potassium thiocyanate at 130°C. for 48 hours afforded a 40% yield of the corresponding 4,6-dithiocyanato derivative 15. 

The reactivity at the C-4 position of hexose and hexoside sulfonates has been demonstrated in the gluco and galacto series and could undoubtedly be extended to other sugars as well. In another example (25), methyl 2,3-di-0-benzoyl-4-0-p-tolysulfonyl-a-D-glucopyranoside (18a) was treated with potassium thiocyanate in N,N-dimethylformamide at 140°C. for 9 hours to give the C-4 epimeric thiocyanato derivative 19 in 34% yield. The corresponding 4-p-bromobenzenesulfonate (18b) however, afforded a 55% yield of 19 in only 2% hours of reaction time. 

Several other methods for the introduction of halo atoms at C-6 in hexose derivatives have been known since the late 1920s. One of the earlier methods involved the reaction of methyl 2,3,4-tri-0-acetyl-6-0-trityl-a-D-glucopyranoside with phosphorus pentachloride which resulted only in an 8% overall yield of methyl 6-chloro-6-deoxy-a-D-glucoside (57). In contrast, the reaction of methyl 2,3,4-tri-0-acetyl-6-0-trityl-a-D-altropyranoside with phosphorus tribromide and bromine afforded a 73% yield of the corresponding 6-bromo-6-deoxy derivative (91). 

Treatment of l,4 3,6-dianhydro-D-glucitol with boron trichloride gives l,6-dichloro-l,6-dideoxy-D-glucitol (20). Although methyl 6-chloro-6-deoxy-a-D-glucopyranoside (isolated as the tribenzoate) could be isolated from the reaction of methyl 3,6-anhydro-a-D-glucopyranoside with boron trichloride (21), the application to the isomeric furanoside derivative led to complex results. 

Sinclair (92) has described an improved method for the preparation of methyl 6-chloro-6-deoxy- -D-glucopyranoside (137) from methyl a-D-glucopyranoside (11). The reaction was effected with sulfur monochloride S2C12 in N,N-dimethylformamide at room temperature and the... 

Methyl 5-deoxy-D-xt/Zo-furanoside. . 207 Methyl 6-deoxy-a-D-glucopyranoside 126 Methyl 4-deoxy-a-D-xylo-... 

The Preparation and Properties of Aryl 2-Deoxy-a-D-glucopyranosides, F. Shaflzadeh and M. Stacey,/. Chem. Soc., (1957) 4612-4615. 

Methyl a-D-glucopyranosid-4-0-yl)pyruvic acid [or methyl 4-0-(oxalomethyl)-a-D-glucopyranoside]... 

Methyl 2-0-(methyl 2-deoxy-a-D-glucopyranosid-2-yl)-a-D-glucopyranoside or bis(methyl 2-deoxy-a-D-glucopyranosid-2 yl) ether... 

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